Metamorphosis of Compton Tortoiseshell Caterpillar in Canada

Subject: What is this caterpillar? Geographic location of the bug: Winnipeg, Manitoba, Canada Date: 06/10/2018 Time: 08:30 PM EDT Your letter to the bugman: I found this caterpillar climbing on my front door yesterday. (picture 1) Today I caught him j’ing (picture 2) He has now turned into a chrysalis. (picture 3) There is a second one of the same sort at the bottom of my door. He is green with a dark head and has barbed setae or spikes. I would like to know what kind of caterpillar he is and what he will become. I hope you can help me. Thanks! How you want your letter signed: Sherrie

Compton Tortoiseshell Caterpillar

Dear Sherrie, How lucky are you???? We have identified your caterpillar as a Compton Tortoiseshell Caterpillar, Nymphalis l-album, thanks to images posted to BugGuide. The caterpillar and chrysalis are described on BugGuide,: “Larva: body speckled and spotted white on pale green, yellow and brown, or blackish, with several rows of branched, usually black spines; head also bears many short spines, with one pair larger and branched near the tip. This is the only Nymphalis species with the pair of branched head horns. Polygonia larvae are similar, though usually with different markings. Pupae: similar to other Nymphalis and to Aglais species, with two points on head end and two rows of conical projections mostly arranged along the dorsum of abdomen + thorax; plus, one prominent point on the mid-dorsum and more along the sides of the thorax.” According to BugGuide, the range is: “southeastern Alaska and across Canada south of the tundra, south in the west to Montana and Wyoming, south in the east to North Carolina and Missouri known to wander; has been recorded as far south as California and Florida, and as far north as Baker Lake, north of treeline in Nunavut.” The chrysalis of the Compton Tortoiseshell is pictured on the John Fowler website. If your luck continues and you are able to witness the emergence of the adult Compton Tortoiseshell, we would love to have you send us the images.

Pre-Pupal Compton Tortoiseshell Caterpillar

Dear Daniel, Thank you so much! I was curious to see what kind of caterpillar it was. The caterpillar crawled up my front door and decided that was the place to stay. Ot was interesting to see him in the j. An hour and a half later he was a chrysalis. Only assuming it was that long because that is when I came back from shopping. I now have another one below my front door, so I have the opportunity to witness two emerge. I hope they do it while I am watching. Do you know how long they will stay in the chrysalis before they emerge? Thank you again, Sherrie

Hi again Sherrie, The actual eclosion date, the day the adult emerges from the chrysalis, may vary depending upon temperature and other weather conditions, but according to BBC: “The chrysalis stage varies between species but is usually around two weeks, whilst the caterpillar inside is undergoes metamorphosis into a butterfly. In order to emerge, they need to be out of direct sunlight, at around 25 degrees and in relatively high humidity.” According to Woodland Trust: “Conversion to a butterfly takes place inside the chrysalis – this process can take several weeks.” According to Sciencing: “Most butterflies take about 10 to 14 days to emerge from their chrysalises.” Many chrysalides change color just prior to pupation, so that might be a hint that eclosion is near.

Chrysalis of a Compton Tortoiseshell

Update: June 23, 2018Hi Daniel, I ended up having 5 Compton Tortoiseshell caterpillars turn into chrysalis around the front of the house. You were right their chrysalis do change color prior to eclosion. I went to get groceries in the morning and noticed that their cocoons had changes color. I came back and I noticed that one had emerged. I was gone only 30 minutes. Sad that I did not get to see the eclosion, just missed it, but happy to see the butterfly resting and finishing his wing development. Beautiful. I have included a close up of my newly emerged Compton Tortoiseshell butterfly. I believe 4 out of the 5 survived and think something happened to the one that cocooned on my front door. Again thank you for your help identifying my caterpillars.

Eclosion of a Compton Tortoiseshell

Thanks for the update Sherrie. We really appreciate the images of the adult to add to your previous posting.

You are welcome. I really wish I had been there a moment earlier to have caught the emergence. And to have seen it open it’s wings. I did see one of the ones that had emerged earlier fluttering around the yard, but was too high to get a close up. Thank you for all your help identifying the Compton Tortoiseshell. Was happy I could get so close and capture all the detail. Sincerely, Sherrie